2008 mercury 4.3 V6 wont go over 3400 rpm

[hostetcj]

I have a 2008 Tahoe 196 with a 4.3 V6 in it. It seemed to run fine all summer then the second to last time out I would put it full throttle and it would only go to 3400 rpm. I could back off completely then full throttle again it would be ok and get to 4600-4800 WOT. The last time I took it out it would not go above 3400 at all. It wouldn't even plane out. Took it to the boat mechanic and he is saying the timing is off. Is this possible without anyone ever being inside of the engine? Also it just seems weird because it ran fine all summer except for the last 2 runs. I am running a 21 prop. Right now I have it winterized and they want to take it out to get the timing right in the spring. I am just not convinced it is a timing issue. Thanks in advance for the help

Chris

 

[Bt Doctur]

Re: 2008 mercury 4.3 V6 wont go over 3400 rpm

Not knowing the service history and maintance repairs make this a guess. timing setting with the elec ign rarely changes that much
bad/poor quality fuel
clogged fuel vent/ restricted fuel flow
weak/damaged fuel pump
worn camshaft for fuel pump
worn out electric fuel pump
carb or injectors bad/clogged/corroded
clogged exaust/burned flaps restricting Y pipe
intake manifold leak
plugs
bottom fouling
too large of prop
poor engine compressionj
detonated piston/ damaged rings
cap/rotor/ plug wires worn/damaged
dead plug or plug wire

To name a few

 

[alldodge]

Re: 2008 mercury 4.3 V6 wont go over 3400 rpm

I have a 2008 Tahoe 196 with a 4.3 V6 in it. It seemed to run fine all summer then the second to last time out I would put it full throttle and it would only go to 3400 rpm. I could back off completely then full throttle again it would be ok and get to 4600-4800 WOT. The last time I took it out it would not go above 3400 at all. It wouldn't even plane out. Took it to the boat mechanic and he is saying the timing is off. Is this possible without anyone ever being inside of the engine? Also it just seems weird because it ran fine all summer except for the last 2 runs. I am running a 21 prop. Right now I have it winterized and they want to take it out to get the timing right in the spring. I am just not convinced it is a timing issue. Thanks in advance for the help

Chris

:welcome: to iboats Chris

Not knowing your serial number I would suggest locating your knock sensor on the side of the block under the exhaust manifold. Pull the wire off of it and if it revs back up then you engine is picking up a knock and retarding the timing to protect itself. If you engine does rev back up, slow the engine back down, put the knock sensor back on and then start pulling plug and dist cap, wires.

 

[Walt T]

Re: 2008 mercury 4.3 V6 wont go over 3400 rpm

Find another tech. If he honestly thinks it's a timing issue then he doesn't know what he's doing and you don't want him near your boat. If he does know what he's doing he's BS'ing you and you don't want him near your boat.

 

[hostetcj]

Re: 2008 mercury 4.3 V6 wont go over 3400 rpm

Not knowing the service history and maintance repairs make this a guess. timing setting with the elec ign rarely changes that much
bad/poor quality fuel
clogged fuel vent/ restricted fuel flow
weak/damaged fuel pump
worn camshaft for fuel pump
worn out electric fuel pump
carb or injectors bad/clogged/corroded
clogged exaust/burned flaps restricting Y pipe
intake manifold leak
plugs
bottom fouling
too large of prop
poor engine compressionj
detonated piston/ damaged rings
cap/rotor/ plug wires worn/damaged
dead plug or plug wire

To name a few

Thanks/ I thought him saying the timing was of seemed wrong. No one to my knowledge has been in the engine. He said there was a scrape on the dist cap that he says someone would of got inside. It is just weird because the boat didn't run right most of the day then at one point it planned out and ran fine but for the ost part it would not plane out and stay around 3400 rpm. I bought the boat at the beginning of last season and the guys I bought it off of said he did just what was needed for the boat with winterization and up keep. I have the oil changed and everything insprceted last year before I put it away for the winter.

Thanks

 

[hostetcj]

Re: 2008 mercury 4.3 V6 wont go over 3400 rpm

:welcome: to iboats Chris

Not knowing your serial number I would suggest locating your knock sensor on the side of the block under the exhaust manifold. Pull the wire off of it and if it revs back up then you engine is picking up a knock and retarding the timing to protect itself. If you engine does rev back up, slow the engine back down, put the knock sensor back on and then start pulling plug and dist cap, wires.

What will that knock sensor tell me if this does work? That I need to replace wires and spark plugs? I probably should do this anyways with the boat being 5 years old and me owning it for the last 2?

Thanks
Chris

 

[hostetcj]

Re: 2008 mercury 4.3 V6 wont go over 3400 rpm

Find another tech. If he honestly thinks it's a timing issue then he doesn't know what he's doing and you don't want him near your boat. If he does know what he's doing he's BS'ing you and you don't want him near your boat.

I really had issues with him saying its a timing issue also. No one to my knowledge has been in the engine. I have owned the boat the last 2 years and had the oil changed, bearings all gone through, lower case oil changed but have not done anything with the plugs or wires. Should I do something with them first? I am in Ohio so the boat is winterized right now so nothing will get done till spring at this point which is frustrating also. I have a mechanic that I went to school with his son in law which works with him but it is not a boat mechanic they work on cars and have boats and do some work on boats. Since its more of a standard engine/plugs/carb problem??

Thanks
Chris

 

[Bondo]

Re: 2008 mercury 4.3 V6 wont go over 3400 rpm

I have a 2008 Tahoe 196 with a 4.3 V6 in it. It seemed to run fine all summer then the second to last time out I would put it full throttle and it would only go to 3400 rpm. I could back off completely then full throttle again it would be ok and get to 4600-4800 WOT. The last time I took it out it would not go above 3400 at all. It wouldn't even plane out. Took it to the boat mechanic and he is saying the timing is off. Is this possible without anyone ever being inside of the engine? Also it just seems weird because it ran fine all summer except for the last 2 runs. I am running a 21 prop. Right now I have it winterized and they want to take it out to get the timing right in the spring. I am just not convinced it is a timing issue. Thanks in advance for the help

Chris

Ayuh,.... Welcome Aboard,.... Sounds Fuel related to me,....

A Complete tune up, 'n service is No doubt a Good idea,...
If yer Bud's up to it, All the Info you could ask for is up in Don'S Adults Only section at the top of the forum,...
Factory manuals are found in the Merc section, just follow the links,...

Spark plug color might lead yer Bud to the answer,...

 

[alldodge]

Re: 2008 mercury 4.3 V6 wont go over 3400 rpm

Just a quick and easy re-post, but my cruiser did the same thing, would not go above 3400 and was running great prior. Turned out it was the knock sensor. The knock sensor was not bad it was just picking up a miss. Let a dealer shot gun it: plugs, wires, distributor cap and rotor. Everything back to normal besides a lighter wallet.

Good luck